Revista Chilena de Historia Natural 81 (4): 575-584, 2008
RESEARCH ARTICLE
Feeding and nutritional ecology of the edible sea urchin Loxechinus albus in the
northern Chilean coast
The red sea urchin Loxechinus albus, an economically important species
occurring along the Chilean littoral benthic systems, has been heavily exploited by artisanal fisheries in recent decades. However,
basic knowledge of its trophic biology is still scarce. Studies of this kind are critical to the successful development of farming
techniques as an alternative to the harvest of natural populations. The aims of this study were to quantify the composition of L.
albus’ natural diet, to determine the assimilation efficiency of the most important dietary components, and to experimentally
examine the species’ trophic selectivity. Adult and juvenile specimens were sampled in spring 1993 and summer, fall and winter 1994
from the shallow subtidal zone of Iquique, northern Chile. Neither juveniles nor adults showed significant seasonal differences in dietary
composition. The main items in the diet were the green alga Ulva sp. for juveniles and the kelp Lessonia sp.
for adults. In adults, assimilation efficiency (as percentage of the total organic matter ingested) was not significantly different among
individuals that consumed Lessonia sp. (48.7 %), Ulva sp. (44.6 %) and Macrocystis (38.1 %),
whereas in juveniles assimilation efficiency was significantly higher for individuals fed on the chlorophyte Ulva sp. (55.4 %),
followed by Lessonia sp. (35.0 %) and Macrocystis (25.5 %). These results suggest that L. albus
undergoes an ontogenetic shift in the diet, consisting of a differential foraging strategy between juveniles and
adults.
Key words:
assimilation efficiency,
Loxechinus, natural diet, trophic selectivity
